This invention relates generally to apparatus to controlling the flow of fluids, and in particular relates to electronic control apparatus for controlling the administration of a plurality of separate fluids independently and consecutively. The basic IV set itself may be of the type described in co-pending application Ser. No. 637,208, filed Dec. 3, 1975, or that shown in co-pending application Ser. No. 637,206, filed Dec. 3, 1975, both assigned to the same assignee as the present invention.
Still more specifically, the present invention relates to electronically controlled intravenous administration sets, wherein electrical circuitry is connected with a plurality of valve operators to operate a plurality of valves in a plurality of intravenous administration sets to control the flow of intravenous fluids from a plurality of separate sources.
Many different types of electronically controlled administration sets are known in the prior art. However, all such sets known to applicant are capable of electronically controlling only one intravenous fluid at a time, and do not have the means or capability of controlling a plurality of fluids by means of a plurality of valves.
Several factors are important in the intravenous administration of fluids, and include, among others, the necessity or desirability of preventing the injection of fluid into the tissue surrounding a vein in the event the needle is improperly inserted or becomes displaced from a vein into which the fluid is to be injected; the desirability of keeping the injection site open, or in other words, of preventing clotting at the injection site in the event the flow through the intravenous set is interrupted or ceases for some reason; the desirability of alarm means to indicate when the unit is not performing properly, as, for example, when the actual flow rate differs from the desired or preset rate; the desirability of the unit to operate even in the event of loss of power from the alternating current supply; the desirability of an accurate and easily read display of the volume and rate of fluid being administered; the necessity of obtaining an accurate and reliable rate of flow through the set; and the ability to control the flow of two separate fluids independently and consecutively, with circuit means connected with a plurality of valves to control the two fluids, and including circuitry to effect automatic switching from one set to the other, as, for example, when one side of the circuit goes into the alarm mode.
Moreover, a very serious problem in hospitals and the like is the occurrence of so-called "runaway" IV sets. This situation arises, for example, when an IV set is set by a nurse or other attendant for the administration of an IV fluid to a patient at a predetermined rate of flow, and subsequently the rate of flow increases for one reason or another. A further problem results from inaccurately setting conventional clamps and the like. The occurrence of flow rate of an intravenous fluid in excess of that desired or set is particularly critical in postoperative procedures, or in any other situation in which the patient has received anesthesia. This is due to the fact that various organs, such as the kidneys of anesthetized persons do not function properly for a brief time after having been anesthetized, and the body does not have the ability to rid itself of fluids at a desired rate. Accordingly, the fluid will build to a point where it can no longer be accommodated by the body's normal functions, and the fluid then begins to build in the person's lungs. This, of course, may result in pneumonia or other serious problems, and in fact, if left unattended, can be fatal.
With the present invention, the problems associated with prior art devices are overcome. More particularly, with the present invention injection of the intravenous fluid into the tissue at an injection site is avoided by making the intravenous administration set of the gravity feed type. The injection site is kept open in the present invention by the provison of the dual control feature, which enables the independent and consecutive control of a plurality of fluids, whereby in the event the primary fluid is exhausted or terminated for one reason or another, the secondary fluid is automatically caused to flow to keep the injection site open. For example, the primary fluid may be a medication or nutriment required after a surgical procedure or the like, and if the source of such fluid is depleted or flow thereof otherwise interrupted for some reason, the circuit automatically switches to the secondary fluid, which may be a saline solution, for example, which may be set at a flow rate considerably less than that of the primary fluid, as, for example, a rate sufficient only to keep the injection site open and prevent clotting thereat.
Also, the circuitry of the present invention includes sensing means for detecting the occurrence of a flow rate other than that set by the attendant and for sounding or giving an appropriate alarm, and also for arresting flow through the malfunctioning side of the apparatus until the situation is corrected. This, of course, prevents either the failure to inject a desired fluid or the injection of an undesired amount of a desired fluid.
Further, the present invention includes both an ac and dc powered capability, whereby the set can continue to operate even in the event of loss of ac power thereto, as, for example, during transport from one location to another or in the event of a power failure or inadvertent unplugging of the set from an ac outlet and the like.
Additionally, the present invention includes an easily read LED display for accurately and reliably indicating the amount of fluid to be dispensed in a metered cycle.
Moreover, the electronic control of the present invention includes a memory capability, whereby it remembers the amount of fluid remaining to be dispensed, in the event a dispensing cycle is interrupted.
Still further, one form of the invention includes a digitally settable clock, and further includes circuitry for time sharing of the clock by the two supply circuits for the respective fluids to be controlled.